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ERC-721 Approved Operator Lookup
x402
ERC-721 Approved Operator Lookup is a paid API for AI agents from twin.unykorn.org, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-29).
Returns the address approved to transfer a specific ERC-721 NFT token on a given EVM chain
Price / call$0.003
Success—
StatusUnknown
How this service works
Which address is approved to move one NFT — Genesis402 / UnyKorn Operator Network
Output
Returns a JSON object indicating success, the approved operator address for the specified NFT token, and a payment receipt including transaction hash, USD amount charged, and a unique receipt ID.
Example use cases
Pre-sale NFT approval audit
“Before I list this NFT for sale, check who is currently approved to move token ID 512 on the contract 0xb47e3cd837dDF8e4c57F05d70Ab865de6e193BBB on Ethereum — I want to make sure no marketplace already has approval.”
NFT custody verification on Base
“Can you check whether any address is approved to transfer token ID 7 from the contract 0x123456789abcdef123456789abcdef1234567890 on Base? I'm doing a custody check before I accept this NFT as collateral.”
Marketplace approval debugging
“I'm debugging a failed NFT transfer — can you look up the approved address for token ID 1001 on contract 0xAbCd1234AbCd1234AbCd1234AbCd1234AbCd1234 on Polygon and tell me what comes back?”
Technical details
Endpoint
POSThttps://twin.unykorn.org/erc721-approved?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to determine the single-token approval (ERC-721 getApproved) for a specific NFT — distinct from operator-level approvals (setApprovalForAll). Prefer this over general blockchain RPC calls when you want a simple pay-per-call REST interface across ten EVM chains without managing your own RPC keys. Best for agents doing NFT custody checks, pre-transfer validations, or marketplace integrations.
Side effects
- Invalid contract address format (not a valid 0x hex address) — returns error
- Token ID does not exist on the given contract — may return null approved address or error
- Unsupported chain name — enum validation failure
- Network timeout or RPC unavailability for the specified chain
- Payment failure via x402 protocol — call not executed
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| params | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"type": "erc721-approved",
"receipt": {
"tx_hash": "0x<64hex>",
"amount_usd": 0.25,
"receipt_id": "g402-<16hex>"
},
"generated_at": "<iso8601>"
}
}Tags
x402
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